If it is possible to quickly and silently start a vehicle, it is preferable to momentarily stop the engine while the vehicle is stopped to reduce fuel consumption and exhaust gas, and a lot of hybrid vehicles are recently provided with an idle stop function.
The shift level is commonly maintained at the D-range (driving) in the idle stop; however, the transmission is shifted to the N-range (neutral) and then returned to the D-range when the driver steps on the acceleration pedal to start the vehicle, in order to softly stop and restart the engine.
When the output torque of the engine is rapidly changed or relatively very large while the transmission is shifted from the N-range to the D-range as described above, shift shock is caused and starting the vehicle is delayed because the transmission is not quickly shifted to the D-range.
A control method of reducing the input torque of the transmission by generating reverse torque in a motor of a hybrid vehicle has been used in the related art to overcome the problem, however, which decreases energy efficiency and is not sufficient to basically overcome the shift shock.